Use #if DCHECK_IS_ON() in base/threading/thread_checker.h

Use
#if DCHECK_IS_ON() in base/threading/thread_checker.h

Use #if DCHECK_IS_ON() instead of
(!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)) in
base/threading/thread_checker.h because it
is same thing and more succinct and centralized.

Committed: https://crrev.com/3e81715e6d3a4324362635aea46ce1f1a163cca1
Cr-Commit-Position: refs/heads/master@{#346574}

[Olli Raula, 2015-08-31 10:33:27]

olli.raula@intel.com changed reviewers:
+ thestig@chromium.org

[Olli Raula, 2015-08-31 10:36:07]

Could you review?

[Lei Zhang, 2015-08-31 21:40:04]

Can you change the subject line and the first line in the CL description to "Use
#if DCHECK_IS_ON() in base/threading/thread_checker.h" ?

[Lei Zhang, 2015-08-31 21:40:10]

Otherwise lgtm

[Olli Raula, 2015-09-01 05:31:42]

The CQ bit was checked by olli.raula@intel.com

[commit-bot: I haz the power, 2015-09-01 05:32:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1324673002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1324673002/1

[commit-bot: I haz the power, 2015-09-01 05:37:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-01 05:37:53]

Patchset 1 (id:??) landed as
https://crrev.com/3e81715e6d3a4324362635aea46ce1f1a163cca1
Cr-Commit-Position: refs/heads/master@{#346574}